POWER TRANSMISSION ELEMENTS AND MECHANISMS 201 



TRANSPORT MECHANISMS 



X X iTranspoH 





•Pafh of 

 tronsporf 



Counter- 

 weights ^v 



Shaff D-- 



A ^ Top of 

 rail 



X-ArHcles 

 moved 



■ Cenier of 

 cran/i arm 



— Pafh of 

 franspori 



'-Paih 



'Shoff 

 Fig. 422. — In this design, a rotary action is used. The shafts Z) rotate in unison and also support the main 

 moving member. The shafts are carried in the frame of the machine and may be connected by either a link motion, a 

 chain and sprocket, or by an intermediate idler gear between two equal gears keyed on the shafts. The rail AA is 

 fixed rigidly on the machine. A pressure or friction plate may be used to hold the material against the top of the rail 

 and prevent any movement during the period of rest. 



/Tronsporf 



Conneciing 

 linl< 



Bearing 



Swivel arm ^ 



Palh of iransporf 



^~ Driven arm 



'Palh of Iransporf 



X= Arficles moved 



Fig. 423. — Here is shown a simple form of link motion which imparts a somewhat egg-shaped motion to the 

 transport. The forward stroke is almost a straight line. The transport is carried on the connecting links. As in 

 design in Fig. 422, the shafts D are driven in unison and are supported in the frame of the machine. Bearings E are 

 also supported by the frame of the machine, and the rail AA is fixed. The details of operation can be understood 

 readily from the figure. 



Transport'-' 



Palhof-' 

 fronsporf 



Li fling lever 



Slops ' 

 Driving arm-' 



A = Top of roil 

 Fric lion slide C 



^ FricHon roil 



Lifting lever 



X = Articles moved 



Fig. 424. — Another type of action. Here the forward and return strokes are accomplished by a suitable mecha- 

 nism, whereas the raising and lowering is imparted by a friction slide. Thus it can be seen from a study of the figure 

 that as the transport supporting slide B starts to move to the left, the friction slide C, which rests on the friction 

 rail, tends to remain at rest. As a result, the lifting lever starts to turn in a clockwise direction. This motion raises 

 the transport which remains in its raised position against stops until the return stroke starts at which time the reverse 

 action begins. An adjustment should be provided for the amount of friction between the slide and its rail. It can 

 readily be seen that this motion imparts a long straight path to the transport. 



